This invention relates in general to hydraulic control units for anti-lock brake systems and in particular to an internal electrical connector for a hydraulic control unit.
An Anti-lock Brake System (ABS) is often included as standard or optional equipment on new vehicles. When actuated, the ABS is operative to control the operation of some or all of the vehicle wheel brakes. A typical ABS includes a plurality of solenoid valves mounted within a control valve body and connected to the vehicle hydraulic brake system. Usually, a separate hydraulic source, such as a motor driven pump, is included in the ABS for reapplying hydraulic pressure to the controlled wheel brakes during an ABS braking cycle. Typically, the pump is mounted within the control valve body and the pump motor is attached to a side of the valve body. An ABS further includes an electronic control module which is electrically connected to the pump motor, a plurality of solenoid coils associated with the solenoid valves, and wheel speed sensors for monitoring the speed and deceleration of the controlled wheels. The electronic control module is typically mounted directly upon the control valve body. The assembled valve body, pump motor and electronic control module form a compact unit which is often referred to as an ABS hydraulic control unit.
During vehicle operation, the ABS electronic control module continuously receives speed signals from the wheel speed sensors. The control module monitors the speed signals for potential wheel lock-up conditions. When the vehicle brakes are applied and electronic components within the control module sense an impending wheel lock-up condition, the control module is operative to actuate the pump motor and selectively operate the solenoid valves to cyclically relieve and reapply hydraulic pressure to the controlled wheel brakes. The hydraulic pressure applied to the controlled brakes is adjusted by the operation of the solenoid valves to limit wheel slippage to a safe level while continuing to produce adequate brake torque to decelerate the vehicle as desired by the driver.
Referring now to FIG. 1, there is shown an exploded perspective view of a typical prior art ABS hydraulic control unit 10. For simplicity, hydraulic fittings for connecting the control unit 10 to vehicle brake components have been omitted from FIG. 1. The hydraulic control unit 10 includes a control valve body 11. As described above, a plurality of solenoid valves (not shown) and a pump (not shown) are mounted within the control valve body 11. A plurality of valve sleeves (not shown), which are associated with the solenoid valves, extend upwardly from the top surface of the valve body 11. Seals are formed between the valve sleeves and the valve body 11 to prevent loss of hydraulic fluid from the vehicle brake system. Each of the valve sleeves encloses an axially movable solenoid armature (not shown) which carries a valve ball on one end.
A pump motor 14 is mounted upon the bottom of the valve body 11. The pump motor 14 has a shaft (not shown) that extends into the valve body 11 to drive a pump. The motor 14 receives electrical power through wires contained in a flexible pigtail 15. The pigtail 15 extends through a vertical bore 16 that is formed through the valve body 11. The lower end of the pigtail 15 terminates in an electrical connector 17 that is attached to a corresponding electrical connector 18 for the motor 14.
A removable electronic control module 20 is attached to the top surface of the valve body 11. The control module 20 includes a box-shaped housing 21 having an open bottom. A seal 22 is disposed between the housing 21 and the valve body 11 to prevent contamination of the interior of the module 20. The housing 21 can be cast from an aluminum alloy or injection molded from a plastic.
A Printed Circuit Board (PCB) 25 is disposed within the control module housing 21. Electrical traces (not shown) are deposited upon the top surface of the PCB 25 by a conventional method. The electrical traces connect electronic components 27 that are mounted upon the PCB 25. The electronic components 27, which include control logic and switching elements for the solenoid valves and motor, are mounted upon the upper surface of the PCB 25. A plurality of solenoid coils 28 for actuating the solenoid valves are mounted upon the lower surface of the PCB 25. When the control module 20 is attached to the valve body 11, each of the valve sleeves extends through an associated solenoid coil 28. When an electric current passes through a solenoid coil 28, a magnetic field is created which causes the armature in the associated valve sleeve to shift and actuate the valve.
An electrical connector 30 is mounted upon the PCB 25 and has an end portion that receives the upper end of the motor pigtail 15. As shown in FIG. 1, the upper end of the pigtail 15 is secured to the connector 30. the electrical connector 30 is, in turn, connected to the control circuit components 27 by the electrical traces. An electrical socket 32 is formed in the control module housing 21. The socket 32 includes a plurality of electrical connectors 33 that are electrically connected to the traces deposited upon the PCB 25. the socket 32 provides an interface with the wheel speed sensors and vehicle power supply.
Typically, a plurality of threaded fasteners 35 attach the electronic control module 20 to the valve body 11. The structure of the control module 20 allows its removal from the valve body 11 for service of the electrical and electronic components without opening the hydraulic brake lines of the vehicle.